Various types of the pin plug have heretofore been commercially available and example of such the pin plug may be found in the Japanese utility model publications Nos. 45-16025, 51-41192, 53-50071 and 53-50070.
A problem of the prior pin plug heretofore used in the audio equipment for example is that a connection between the plug and the connecting cord is unstable and the latter is apt to disengage from the former or to cause a defective contact because the plug is usually disengaged from a jack by pulling the connecting cord.